Objective In order to screen safe and effective fungicides to provide guidance for passion fruit production, seven biological fungicides were used as materials to study their control effects on the pathogen causing stem rot disease in passion fruits.

Method Seven botanical and microbiological fungicides were used to determine their toxicity effects on the pathogen causing stem rot disease in passion fruits by mycelium growth rate method, the effects of fungicides on mycelium growth and spore morphology were observed, and their control effects were tested by in vivo inoculation method.

Result All the selected fungicides showed inhibition effects on mycelium growth but had different effects on spore growth and morphology. Based on the indoor toxicity test results, among the botanical fungicides, Jinggangmycin showed the best inhibition effect with an EC₅₀ of 7.79 mg/L, followed by Chunleimycin, ethylallicin and matrine, with the EC₅₀ of 26.35 mg/L, 28.65 mg/L and 339.13 mg/L, respectively. Polyxins showed the lowest effect with an EC₅₀ of 1 150.29 mg/L. Microbiological fungicide of Bacillus subtilis showed better effect than Trichoderma harzianum, with an EC₅₀ of 3.2×106 CFU/g. The four screened fungicides of Jinggangmycin, Chunleimycin, ethylallicin and B. subtilis showed antifungal effects on different strains of fusarium pathogen. The in vivo inoculation test and field test showed that Jinggangmycin and B. subtilis had remarkable control effects on the pathogen causing stem rot disease in passion fruits, with in vivo inoculation control efficacy of 58.8% and 70.6%, respectively, and field control efficacy of 53.7% and 61.3%, respectively.

Conclusion Two biological fungicides of B. subtilis and Jinggangmycin were screened out for their optimal control effects on the stem rot disease in passion fruits. It can provide alternatives or effective supplements for chemical fungicides for the control of stem rot disease, which could be promoted and applied.